Electronic devices typically use a graphical display to display information to a user of the device, and to indicate the status of various parameters of the device, such as battery charge level. There are a variety of display technologies in common use, including liquid crystal, light-emitting diode, and electrophoretic displays, to name a few of the more commonly used display technologies. Recently, a special type of electrophoretic display is becoming more popular. It uses encapsulated electrophoretic material. Bichromal electrically charged microspheres are encapsulated in small capsules to prevent the problems normally associated with electrophoretic displays, namely clustering and settling. Encapsulated electrophoretic displays are bistable, as well, meaning they can be set and then the power turned off and the display will retain the image of whatever is being displayed. Thus, it makes an excellent choice for portable, battery powered devices such as cellular phones.
Generally, displays can be categorized into one of two categories. First, there are displays designed for general purpose use. General purpose displays typically use an active matrix driven to provide control over individual pixel elements. The device outputs graphical information to be displayed to a display driver, which activates the appropriate pattern in the matrix such that a representation of the information is viewable to the user. A second type of display is a segmented display with segments formed into unique shapes or symbols to be displayed at a fixed location on the display. For example, a battery meter may be configured of several adjacent bar segments. These symbols are simply turned on or off in correspondence with the status of the subsystem or parameter of the device to which they pertain. The second category of display is simpler because it requires one less driver layer, and fewer drive conductors for the drive layer.
Each type of display has advantages and disadvantages. Matrix type displays are manufactured in high volume, and can be used to display a wide variety of random information. However, they are typically manufactured in specified sizes, and driving them requires a relatively complex layout. Segmented displays are simple, and are easily custom made, but may be more expensive. They also are fixed, and therefore can only display or indicate an image in the shape of their segments, or combinations of segments. Therefore there is a need for a display technology that takes advantage of both modes of driving the display.